Waveguides generally support well-defined modes. Waveguides may typically allow storage, conversion and transmission of energy and information in physical excitations that exhibit wave-like properties. Non-ideal properties of conventional waveguides may generally be classified into: scattering (into other modes of the same elementary excitation), nonlinear conversion (again, into other modes of the same elementary excitation), dispersion (dependence of wave properties on excitation energy), polarization (the interaction of multiple substantially identical wave excitations of the same type) and absorption (i.e., transfer of energy to modes of other elementary excitations). Photonic waveguides, such as planar optical dielectric waveguides, are typically composed of materials such as glass, compound semiconductors, silicon-based materials and polymers.
It is believed to be desirable to reduce scattering and absorption in photonic waveguides in order to decrease losses in propagating modes. Waveguides exhibiting such reductions may be attractive for use with low-loss optical delay lines in on-chip photonic circuits for analog optical signal processing, for example. Such waveguides may also prove particularly useful in high power semiconductor amplifiers and lasers, such as amplifiers and lasers for telecommunications and directed-energy applications. High-efficiency electro-optic modulators well suited to introduce photonic signals into RF systems and provide more powerful signal processing capability and lighter weight, smaller size and wireless capabilities may also benefit from such waveguides. Further, more-nearly ideal photonic oscillator sources, such as sources that exhibit narrow line-width, high-spectral purity oscillators, and ultra-low-jitter pulsed sources may be achievable. Such devices would be useful for advanced signal processing and communications applications that introduce the advantages of digital signal processing into domains conventionally served by analog systems. Some examples include software radio, secure communications, high-spectral-efficiency communications, low-probability-of-intercept communications, spread-spectrum radar/synthetic-aperture-radar, and laser ranging/imaging.